The serio driver provides low-level access to the serial port control lines.

The digout bitfield of dio interface command structure needs lowest two bits to be filled: 0 - new RTS line state (output line) 1 - new DTR line state (output line)

This driver provides data by filling bits bitfield of dio interface data structure. Lowest six bits are filled by the driver: 0 - current RTS line state (output line) 1 - current DTR line state (output line) 2 - currend DCD line state (input line) 3 - current CTS line state (input line) 4 - current DSR line state (input line) 5 - current RI line state (input line)